Ceanothus is a genus of about 50–60 species of nitrogen-fixing shrubs and small trees in the buckthorn family (Rhamnaceae). Common names for members of this genus are buckbrush, California lilac, soap bush, or just ceanothus. "Ceanothus" comes from Ancient Greek: κεάνωθος (keanōthos), which was applied by Theophrastus to an Old World plant believed to be Cirsium arvense.
Adenostoma fasciculatum, commonly known as chamise or greasewood, is a flowering plant native to California and Baja California. This shrub is one of the most widespread plants of the California chaparral ecoregion. Chamise produces a specialized lignotuber underground and at the base of the stem, known as a burl, that allow it to resprout after fire has off burned its stems. It is noted for its greasy, resinous foliage, and its status as one of California's most iconic chaparral shrubs.
Ceanothus integerrimus, known by the common name deer brush, is a species of woody shrub in the family Rhamnaceae, native to the western United States in Arizona, New Mexico, California, Oregon, and Washington. It grows in montane chaparral and woodlands regions, in hardwood forests, and in fir, spruce, and Ponderosa pine plant communities, being most abundant in the California chaparral and woodlands and Sierra Nevada.
Ceanothus arboreus is a species of perennial shrub to small tree in the family Rhamnaceae, commonly known as the feltleaf ceanothus, island ceanothus, and island mountain lilac. It is the largest member of the California lilacs, and is characterized with glossy, dark green foliage that is adorned by pale blue to white flowers in bloom. It is endemic to the Channel Islands of California and Guadalupe Island in Mexico, only being re-discovered on Guadalupe Island after the elimination of feral goats.
Ceanothus cyaneus is a species of flowering shrub in the genus Ceanothus known commonly as the San Diego buckbrush and Lakeside ceanothus. This species is found in the Peninsular Ranges of San Diego County, California, and known from one occurrence in Baja California. It is characterized by brilliant blue flowers, glossy green foliage, and is regarded as one of the most beautiful members of the genus.
Euphorbia misera is a semi-succulent shrub in the genus Euphorbia commonly known as the cliff spurge or coast spurge. A drought-deciduous shrub, it is typically found as a gnarled, straggly plant occupying seashore bluffs, hills and deserts. Like other members of its genus, it has a milky sap, which can be found exuding out of the light gray bark when damaged. The alternately-arranged leaves are round and folded in the middle, with small hairs on them. The "flowers" can be found blooming year-round, and are colored maroon or yellow in the center with 5 white to light-yellow petal-like appendages attached outside. This species is native to the Baja California peninsula and Sonora in Mexico, and the coast of southern California in the United States, where it is a rare species. It is threatened in some localities by the development of its coastal habitat, which tends to be prime locations for high-end residential and commercial developments.
Ceanothus spinosus, with the common names greenbark and redheart, is a species of Ceanothus. It is native to southern California and northern Baja California, where it grows in the scrub and chaparral of the coastal mountain ranges.
Ceanothus cordulatus is a species of shrub in the family Rhamnaceae known by the common names mountain whitethorn and whitethorn ceanothus. It is native to California and adjacent sections of Oregon, Nevada, and Baja California, where it grows on mountain ridges and other forested areas. This is a spreading shrub growing usually wider than tall and up to about 1.5 meters. The stems are gray, with the twigs yellow-green in color and fuzzy in texture when new. The evergreen leaves are alternately arranged and up to 3 centimeters long. Each is oval in shape with three ribs and generally not toothed. The leaves may be hairy or not. The inflorescence is panicle-shaped, up to about 4 centimeters long. The flowers are white to off-white with five sepals and five petals. The fruit is a rough, ridged capsule up to half a centimeter long. It has three valves inside, each containing a seed. It is a nitrogen-fixing plant, that is uniquely abundant in old-growth forest conditions when compared to similar types of nitrogen-fixing plants. In addition, Ceanothus cordulatus is known to be an important source of nitrogen patches for significantly longer times than other similar post-disturbance successional shrubs, following disturbance events such as forest fires.
Ceanothus fresnensis is a species of shrub in the family Rhamnaceae known by the common name Fresno mat. It is endemic to California, where it grows in central sections of the Sierra Nevada and its foothills. Its habitat includes dry woodland and coniferous forest.
Ceanothus pauciflorus, known by the common name Mojave ceanothus, is a species of flowering shrub in the buckthorn family, Rhamnaceae. It is native to the Southwestern United States and Mexico, where it grows primarily in shrubland communities at moderate to high elevations. It is characterized by oppositely arranged leaves, corky stipules and white flowers. It was formerly known as Ceanothus greggii.
Ceanothus lemmonii is a species of shrub in the family Rhamnaceae known by the common name Lemmon's ceanothus. It is endemic to California, where it grows on the wooded slopes of the Inner North Coast Ranges and the Sierra Nevada foothills to the west and east, respectively, of the Sacramento Valley.
Ceanothus leucodermis, with the common names chaparral whitethorn or chaparral white thorn, is a species of shrub in the family Rhamnaceae. This Ceanothus is an importance browse for several types of ungulate, such as the mule deer and bighorn sheep, who prefer the new growth and shoots to the older, spiny parts.
Ceanothus oliganthus is a species of shrub in the family Rhamnaceae known by the common name hairy ceanothus or hairy-leaf ceanothus.
Ceanothus prostratus is a species of shrub in the family Rhamnaceae. Common names include prostrate ceanothus, pinemat, and mahala mat. It is native to the Pacific Northwest of the United States where it grows in coniferous forests and open plateaus.
Ceanothus pumilus is a species of shrub in the family Rhamnaceae known by the common names dwarf ceanothus and Siskiyou mat.
Ceanothus roderickii is a rare species of shrub in the family Rhamnaceae known by the common name Pine Hill ceanothus. It is endemic to western El Dorado County, California, where it grows in the chaparral and woodlands of the Sierra Nevada foothills, such as the Pine Hill Ecological Reserve. It is named after 20th century California flora explorer, botanist, and arboretum director Wayne Roderick.
Ceanothus tomentosus, with the common name woollyleaf ceanothus, is a species of shrub in the family Rhamnaceae. It is characterized by pale-blue to deep blue flowers and wooly leaves. It is native to California and Baja California, having an unusual disjunct distribution in the Peninsular Ranges and the north-central Sierra Nevada.
Ceanothus verrucosus is a species of shrub in the family Rhamnaceae known by the common names wart-stem ceanothus, barranca brush, coast lilac and white coast ceanothus. It is endemic to northwestern Baja California and San Diego County, where it grows in coastal sage scrub and coastal succulent scrub habitats. It is considered a rare species north of the international border, as most of the valuable coastal land that hosts this plant in the San Diego area has been claimed for development. In California, several extant populations still remain scattered around the region, such as one protected at Torrey Pines.
Ceanothus herbaceus, also known as Jersey tea, is a species of shrub in the family Rhamnaceae and is similar to Ceanothus americanus and Ceanothus sanguineus. It is a perennial shrub which is native to North America.
